The present invention relates to an analog display device of the value of at least one function represented by an information composed of a certain number of logic states. There exists already very numerous analog display devices of the value of a function by means of a needle or an index co-operating with a graduated dial. In certain cases, the displacement of the needle is in a direct relation with the function to be measured. For example, in the anemometers and the bathymeters, the needle is directly set into motion by a transducer sensitive to the pressure and in the galvanometers, the needle is directly displaced by a transducer sensitive to the electric current. However, in numerous applications, the displacement of the needle is an indirect relation of the function to be measured. For example, in very numerous electrical measuring instruments, the function is at first converted in an electric current having a value proportional to the value of the function and then displayed by means of a galvanometer. Such a method, although very widely utilized, has many drawbacks. On the one hand, the proper error of the galvanometer is added to the measuring error and, on the other hand, the galvanometers are very often sensitive to the shocks and vibrations.
By another way, and more and more often, the measuring and control instruments make use of the digital technique wherein the value of the function is represented by an information composed of a succession of logic states which may be displayed directly by means of digital displays. For this reason, and also because they require analog-digital converters which are relatively expensive, the analog displays are more and more often abandoned. However, there still exist numerous applications where the analog display is superior in comparison with the digital display. This is the case when one desires a rapid appreciation of the value of the function.
As an example, in the motor cars, the digital displays are not well accepted by the drivers. It is already known however, that in this domain, the microprocessor will soon be introduced. The microprocessor shall centralize all the measurements required for the good running of the car and the results of these measurements shall be expressed in digital form. However, from the point of view of the driver, it would still be desirable that these results be displayed in analog form.